152 lines
5.6 KiB
Markdown
152 lines
5.6 KiB
Markdown
---
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id:
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aliases: []
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tags:
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- topic/electrical
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- type/media
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---
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# 314.28 Pull and Junction Boxes and Conduit Bodies.
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Boxes and conduit bodies used as pull or junction boxes
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shall comply with 314.28(A) through (E).
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> [!exception]
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> Terminal housings supplied with motors shall comply with
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> the provisions of 430.12.
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## (A) Minimum Size.
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For raceways containing conductors of 4 AWG or larger that are required to be insulated,
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and for cables containing conductors of 4 AWG or larger,
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the minimum dimensions of pull or junction boxes installed in a raceway or cable run
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shall comply with 314.28(A)(1) through (A)(3).
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Where an enclosure dimension is to be calculated based on the diameter of entering raceways,
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the diameter shall be the metric designator (trade size)
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expressed in the units of measurement employed.
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### (1) Straight Pulls.
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In straight pulls,
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the length of the box or conduit body
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shall not be less than eight times the metric designator (trade size)
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of the largest raceway.
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### (2) Angle or U Pulls, or Splices.
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Where splices or where angle or U pulls are made,
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the distance between each raceway entry inside the box or conduit body
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and the opposite wall of the box or conduit body
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shall not be less than six times the metric designator (trade size)
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of the largest raceway in a row.
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This distance shall be increased for additional entries
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by the amount of the sum of the diameters of all other raceway entries
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in the same row on the same wall of the box.
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Each row shall be calculated individually,
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and the single row that provides the maximum distance shall be used.
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> [!exception]
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> Where a raceway or cable entry is in the wall of a box or conduit body
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> opposite a removable cover,
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> the distance from that wall to the cover
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> shall be permitted to comply with the distance required
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> for one wire per terminal in Table 312.6(A).
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The distance between raceway entries enclosing the same conductor
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shall not be less than six times the metric designator (trade size)
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of the larger raceway.
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When transposing cable size into raceway size in 314.28(A)(1) and (A)(2),
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the minimum metric designator (trade size) raceway
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required for the number and size of conductors in the cable shall be used.
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### (3) Smaller Dimensions.
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Listed boxes or listed conduit bodies
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of dimensions less than those required in 314.28(A)(1) and (A)(2)
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shall be permitted for installations of combinations of conductors
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that are less than the maximum conduit or tubing fill
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(of conduits or tubing being used)
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permitted by Table 1 of Chapter 9.
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Listed conduit bodies of dimensions less than those required in 314.28(A)(2),
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and having a radius of the curve to the centerline
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not less than that indicated in Table 2 of Chapter 9
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for one-shot and full-shoe benders,
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shall be permitted for installations
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of combinations of conductors
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permitted by Table 1 of Chapter 9.
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These conduit bodies shall be marked
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to show they have been specifically evaluated
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in accordance with this provision.
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Where the permitted combinations of conductors
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for which the box or conduit body has been listed
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are less than the maximum conduit or tubing fill permitted by Table 1 of Chapter 9,
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the box or conduit body shall be permanently marked
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with the maximum number and maximum size of conductors permitted.
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For other conductor sizes and combinations,
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the total cross-sectional area of the fill
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shall not exceed the cross-sectional area
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of the conductors specified in the marking,
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based on the type of conductor identified
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as part of the product listing.
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> [!info]
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> Unless otherwise specified,
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> the applicable product standards evaluate the fill markings covered here
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> based on conductors with Type XHHW insulation.
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## (B) Conductors in Pull or Junction Boxes.
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In pull boxes or junction boxes having any dimension over 1.8 m (6 ft),
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all conductors shall be cabled or racked up in an approved manner.
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## (C) Covers.
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All pull boxes, junction boxes, and conduit bodies
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shall be provided with covers compatible with the box or conduit body construction
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and suitable for the conditions of use.
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Where used, metal covers shall comply with the grounding requirements of 250.110.
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## (D) Permanent Barriers.
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Where permanent barriers are installed in a box,
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each section shall be considered as a separate box.
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## (E) Power Distribution Blocks.
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Power distribution blocks shall be permitted
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in pull and junction boxes over 1650 cm3 (100 in.3)
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for connections of conductors where installed in boxes
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and where the installation complies with 314.28(E)(1) through (5).
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> [!exception]
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> Equipment grounding terminal bars shall be permitted in smaller enclosures.
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### (1) Installation.
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Power distribution blocks installed in boxes shall be listed.
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Power distribution blocks installed on the line side of the service equipment
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shall be listed and marked "suitable for use on the line side of service equipment" or equivalent.
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### (2) Size.
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In addition to the overall size requirement in the first sentence of 314.28(A)(2),
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the power distribution block shall be installed in a box
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with dimensions not smaller than specified in the installation instructions
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of the power distribution block.
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### (3) Wire Bending Space.
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Wire bending space at the terminals of power distribution blocks
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shall comply with 312.6.
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### (4) Live Parts.
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Power distribution blocks shall not have uninsulated live parts exposed within a box,
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whether or not the box cover is installed.
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### (5) Through Conductors.
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Where the pull or junction boxes are used for conductors
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that do not terminate on the power distribution block(s),
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the through conductors shall be arranged
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so the power distribution block terminals are unobstructed following installation.
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